This application claims foreign priority from DE 102 48 644.1, filed Oct. 13, 2002, the contents of which are incorporated herein by reference.
FIG. 1 is selected for publication on the face of the face of the patent.
1. Field of the Invention
The present invention relates to a power semiconductor module having improved configuration technology. More specifically, the present invention relates to a power semiconductor module with a base plate and/or being configured for direct or indirect installation on a heat sink or other cooling body, with active and/or passive components and improved configuration and electro-conductive features.
2. Description of the Related Art
Power semiconductor modules, in particular those including a power converter module, are known to have a base plate or for direct installation on a heat sink, with active and/or passive components. Several such power semiconductor modules are known from the literature. When the capacity is increased, especially by using modern power semiconductor components with higher cooling requirements, the conventional art cannot meet these requirements. Consequently, the present invention provides other methods of configuration technology that are absolutely necessary for the individual parts.
Modern power semiconductor modules, which are the starting point of this invention, are modules without base plates, such as described in DE 199 03 875 C2, the contents of which are herein incorporated by reference, consisting of:
a packaging,
a ceramic substrate with circuit-friendly metallic laminations such as those made according to the DCB (direct copper bonding) method;
components positively bonded to this substrate by soldering, such as diodes, transistors, resistors or sensors;
bonds to connect the structured side of the components with other components, the substrate and/or connecting elements leading outside;
a sealing compound preferably made of silicon rubber, to insulate the individual components from each other.
A configuration technology with pressure contact for the thermal contacting of the module on a heat sink has proven very advantageous for such power semiconductor modules. Unfortunately, this pressure contact configuration technology has been shown in particular, that the quality of large-surface soldering bonds is very difficult to control, which is greatly detrimental to the reliability and service life (premature failure) of the power semiconductor modules. This type of pressure contact bond has uniformity, homogeneity, and substantial quality control problems that increase greatly with the areas being pressure-contact-bonded.
Preferably, the pressure configuration in such pressure-contacted power semiconductor modules is achieved with a mechanically stable pressure plate. Depending on the further development, the generated pressure can be transmitted to the substrate either by means of special pressure plate designs (as shown, for example, in DE 196 48 562 C2) or by means of an elastic pressure accumulator according to DE 199 03 875 C2, the contents of both references are herein incorporated by reference as background material.
In such pressure-contacted power semiconductor modules, a heat-conducting medium is provided in an effort to establish full-surface thermal conduct and thus to compensate for any unevenness or non-uniformity on the heat sink and/or the substrate underside between the power semiconductor module and the heat sink. The non-uniformity of surface between the two opposing surfaces for pressure contacting can magnify the difficulties where any defects are complementary and additive.
In the power semiconductor modules according to DE 196 48 562 C2 or DE 199 03 875 C2, as well as power semiconductor modules known in prior art, with a base plate or for direct installation on a heat sink, each has the distinct disadvantage that heat dissipation to a cooling element, such as a heat sink, is subject to high thermal resistance, or thermal resistivity (the inverse of thermal conductivity). The more marginal areas exist between the power semiconductor module generating the heat and the heat sink, the greater the thermal transfer resistance. In comparison with metals, flexible thermally conducting layers such as heat-conductive paste, have clearly higher heat resistance. Therefore, the efficient dissipation of heat from a power semiconductor module to a heat sink is a substantial component of highly efficient compact configuration topologies.
Another disadvantage of conventional power semiconductor modules with a base plate or designed for direct installation on a heat sink is that modern power semiconductor components, as commonly used, have a higher current load capacity per relative chip area and consequently produce much more waste heat per unit of area. Unfortunately, the thermal connection between an advantageously metal-laminated substrate and the power semiconductor component is already a limiting factor for the efficiency of a power semiconductor module. At present, the heat generated in the power semiconductor component can still be dissipated by means of existing connection methods, usually soldering bonds.
In considering future chip generations, the thermal conductivity of the connection between the power semiconductor component and the substrate, will have an even more limiting effect on efficiency. Furthermore, the connections named above are presently at the limit of their current load capacity. In that respect, too, the electrical connection between the power semiconductor component and the substrate will determine the efficiency of the power semiconductor module
In summary, the problems with commercially available power semiconductor modules include at least the following:
1. Incapable thermal conductivity between semiconductor components and a substrate and/or a substrate and a heat sink or cooling body or means for cooling.
2. Non-uniform pressure contacting and non-uniform bonding resulting in the potential for hot-spots and weak-spots where the pressure contact bonding is insecure or non-uniform.
3. The electrical load capacity of present designs is limited by the pressure contact bonding between components.
4. Difficulty in uniformly forming a pressure contact bond between a metal-laminated surface of a substrate with either a power semiconductor component and/or a heat sink, cooling body, or other means for cooling and further transmitting any received thermal energy.
Another object of the present invention is to provide a power semiconductor module that overcomes the disadvantages noted above.
It is another object of the present invention is to provide a power semiconductor module with improved cooling ability while retaining module strength and electro-conductive characteristics.
It is another object of the present invention to provide an improved uniformity of a thermal bond between a substrate and a power semiconductor component.
It is another object of the present invention is to present a power semiconductor module in which the electrically and thermally conductive connection between at least one power semiconductor component and a substrate and/or the thermally conductive connection with a heat sink or cooling body or other means for cooling the power semiconductor module that has a reduced thermal and optionally also electrical resistance.
It is a further object of the present invention to present a power semiconductor module easily adapted in multiple embodiments beyond those shown herein as along as the invention, as described herein, is embodied.
It is another object of the present invention to create a thermally conductive paste including carbon based tubules resulting in a thermally conductive paste with better thermal conductivity than the prior art by at least about two orders of magnitude.
The present invention relates to a power semiconductor module, in particular a power converter module, with a base plate or for direct installation on a heat sink, cooling body, or other means for thermally cooling. The power semiconductor module consists of generally a packaging (not shown), at least one power semiconductor component and at least one insulating substrate on whose first surface a metallic layer is provided. Additional items and components may be optionally added to the present power semiconductor module as needed to meet the needs of any circuit design without departing from the teachings herein. Carbon nano tubules (having a very small size) are used for at least one of a thermal and partly electrical contacting, on at least one of the top side and a bottom side of a substrate for contacting the power semiconductor component with the metallic layer and on the other side to connect the substrate with the heat sink or cooling body.
According to one embodiment of the present invention there is provided a power semiconductor module, comprising: at least one thermally conducting supporting member, at least one power semiconductor component, t least one insulating substrate having a first surface between the power semiconductor component and the substrate, a metallic layer on the first surface, and at least a first thermal conduction layer comprising at least a plurality of carbon based tubules between the metallic layer on the first surface and the power semiconductor component, whereby a thermal conductivity is improved.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the supporting member includes at least one of a base plate, a heat sink, a cooling member, and a means for transferring thermal energy away from the substrate and the at least one power semiconductor component.
According to another embodiment of the present invention, there is further provided a power semiconductor module, further comprising: a packaging in the power semiconductor module, and the packaging at least partially bounding the power semiconductor module, whereby the packaging aids an assembly and a use of the power semiconductor module.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the carbon-based tubules are arranged substantially orthogonal to the plane of the substrate.
According to another embodiment of the present invention, there is further provided a power semiconductor module, further comprising: at least a second surface on the insulating substrate between the substrate and the thermally conducting support member, and at least a second thermal conduction layer comprising a plurality of carbon based tubules between the second surface and the support member, whereby a thermal conductivity is improved.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the plurality of tubules in the first layer extends substantially orthogonal to the substrate.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the plurality of tubules in the first and the second layers extends substantially orthogonal to the substrate.
According to another embodiment of the present invention, there is further provided a power semiconductor module, further comprising: at least a second surface on the substrate, opposite the first surface, a second metallic layer on the second surface, at least a second thermal conduction layer comprising a plurality of carbon based tubules between the second metallic layer and the supporting member.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the carbon-based tubules include at least a plurality of carbon-nano tubules.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the at least one power semiconductor component and the first thermal conduction layer are positively bonded to the substrate by means of a pressure contact.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the second conduction layer is a pasty mixture comprising the plurality of carbon based tubular members and a bonding agent, whereby the pasty mixture forms a conductive past.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the power semiconductor module is arranged on the conducting supporting member by a means for applying a pressure contact.
According to another embodiment of the present invention, there is further provided a power semiconductor module, further comprising: a second thermal conductive layer between the substrate and the supporting member, and the second layer being a pasty mixture comprising at least a plurality of carbon based tubules and a bonding agent.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: a thermal conductivity of the pasty mixture is about two orders of magnitude less thermally conductive than a conventional pasty mixture.
According to another embodiment of the present invention, there is further provided a power semiconductor module, comprising: at least one means for thermally conducting and supporting the power semiconductor module, at least one power semiconductor component, at least one insulating substrate having a first surface between the power semiconductor component and the substrate, a metallic layer on the first surface, at least a first thermally conduction layer including at least a plurality of carbon based tubules between the metallic layer on the first surface and the power semiconductor component, and at least a second thermally conduction layer including at least a plurality of carbon based tubules between the insulating substrate and the means for thermally conducting and supporting, whereby a thermal conductivity from the power semiconductor component to the means for thermally conducting and supporting is greatly improved.
According to another embodiment of the present invention, there is further provided a power semiconductor module, further comprising: at least a first metallic layer on a first side of the substrate, between the fist thermally conductive layer and the substrate, and at least a second metallic layer on a second side of the substrate, between the second thermally conductive layer and the substrate, whereby a thermal conductivity of the module is increased.
According to another embodiment of the present invention, there is provided a method for manufacturing a power semiconductor module, comprising the steps of: forming a first metallic layer on a top surface of a substrate, forming a first thermally conductive layer between one of a bottom surface of a power semiconductor component and the first metallic layer, the first thermally conductive layer including a plurality of carbon based tubules, positively bonding the power semiconductor component and the first thermally conductive layer on the first metallic layer of the substrate, forming a second thermally conductive layer between one of a bottom surface of the substrate and a top surface of a thermally conducting support member, positively bonding the second substrate and the second thermally conductive layer to the support member, whereby a power semiconductor module is formed having a very easy thermal conductivity from the power semiconductor component to the support member.
According to another embodiment of the present invention there is provided a power semiconductor module, comprising: at least one power semiconductor component, at least one substrate, at least one metallic layer on at least a first surface of the substrate, at least one thermally conducting support member, at least one thermally conducting layer between at least one of the power semiconductor component and the substrate, and the substrate and the support member, and the at least one thermally conducting layer including a plurality of carbon based tubular components, whereby a thermal conductivity of the power semiconductor module is increased.
According to another embodiment of the present invention, there is provided a power semiconductor module, with a base plate or for direct installation on a heat sink, comprising: packaging surrounding at least a portion of the module, at least one power semiconductor component, at least one insulating substrate on whose first surface a metallic layer is provided, whereby the at least one power semiconductor component is connected with the metallic layer by means of a layer containing carbon nano tubules running substantially orthogonal to the substrate planes, whereby the substrate is additionally connected with one of the base plate and the heat sink by means of a layer of carbon nano tubules.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: an additional metallic layer is provided on the second main surface between the substrate and the layer of carbon nano tubules.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the at least one power semiconductor component including its carbon nano tubules is positively bonded to the substrate by means of a pressure contact.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the power semiconductor module is arranged on the base plate or the heat sink by means of pressure contact.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the carbon nano tubules are arranged directly on the power semiconductor component.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the carbon nano tubules are arranged on at least one metallic layer of the substrate.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the carbon nano tubules are arranged substantially orthogonal to a substrate plane.
According to another embodiment of the present invention, there is further provided a power semiconductor module, wherein: the carbon nano tubules are arranged between the substrate and the base plate or the heat sink in a pasty mixture of carbon nano tubules and a bonding agent, selected from a group including a silicon oil.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conduction with the accompanying drawings, in which like reference numerals designate the same elements.